In contemporary designs of battery chargers, one or more batteries are subjected to nearly continuous recharging when not in use. For example, in the circuit of U.S. Pat. No. 5,130,634 describing a BATTERY CHARGER FOR A PORTABLE WIRELESS TELEPHONE SET HAVING MEANS FOR TRICKINGLY CHARGING THE BATTERY WITH AN INCREASED CURRENT DURING A STAND-BY PERIOD OF THE TELEPHONE SET, by Kasai, three different charging operations, each characterized by different charging currents, are used in an effort to maintain the battery pack at its normal charge amplitude despite current drain during standby operation. Generally however, when a rechargeable battery pack installed with a device is fully charged by a charging device, if the corresponding battery is a new and unused one, or has not been used for a long time, the maximum charge capacity can not be obtained. This is due to a chemical reaction of the battery, and occurs since the charging is being attempted with a corresponding battery which has not been fully charged, during charging. Also, the charging device typically performs a rapid charging operation, so that a charging operation is performed to place the battery in a fully charged state having a normal voltage within a short time.
In this case, the charging device senses the charged voltage state of the battery, and if the charging voltage is sensed as exceeding a predetermined voltage, full-charging is indicated. In case of a new battery or a battery unused for a long time however, since the corresponding battery is non-activated, full-charging is inaccurately indicated as described above without completion of maximum charging. Accordingly, when an insufficiently charged battery is used, the maximum charge capacity can not be obtained and a low capacity state appears, therefore, the battery has a very short discharging time in comparison to a battery having a maximum capacity, when the battery is inserted for use in an applied system.
Accordingly, when the non-activated battery has been charged as described above and is inserted for use in the applied system, the short discharging time causes repeated inconvenience.